Intake manifold won't seal - How do I check it ?

I had a similar issue with the 360 I put in my 73 sport. Top of intake gasket crushed down nicely - bottom did not and leaked oil into the intake ports. Tried using sealants on new gaskets, thicker gaskets etc - no good. I knew I had machined the head for compression .030", but figured it was not enough to need a correction on the intake face of the head. WRONG. I never was able to get the intake to seal properly until I had the intake machined (.095 per .010) and it fixed it. Sealed up perfectly.

On my manifold (dual plane Weiand) I was able to site down a couple of the intake runners and see the misalignment from the carb plenum. If you port matched the intake and head to the gasket, you'll see it.